1. Field of the Invention
This invention concerns a track mounting type magnetic levitation transport system which performs non-contact transport of objects to be transported by attraction type magnetic levitation; the objects to be transported being made of ferromagnetic bodies such as steel plate.
2. Description of the Prior Art
For example, when transporting steel plate between steel plate processing equipment in the cold rolling process at a steel works, normally, a transport method using a roller track, in which multiple rollers are arranged in the direction of transport, is adopted. Also, in steel plate press processing at car plants and the like, generally, a transport method is adopted in which the steel plates to be pressed are transported to the pressing equipment using bogies or cranes.
However, with the method using roller tracks, if there is any dirt, etc. on the rollers, the surface of the steel plate which the track transports is liable to be scratched. Thus, there is a risk of significant reduction of the product quality. For this reason, the rollers must always be serviced so that dirt and the like does not adhere to the rollers. Thus, there is the problem of requiring large amounts of labour and cost. Also, with the bogie or crane methods, there are the problems that, not only is the steel plate liable to scratching when loading or unloading, but also a great deal of time is expended on the movement.
Therefore, currently, various systems are under development to resolve problems such as these. A system for the non-contact support of steel plate has been developed (Nikkei Mekanikaru, Jun. 12, 1989). In this, for instance, multiple electromagnets are laid in a track and these electromagnets are successively excited where the end of the steel plate, which moves along a track beneath the electromagnets, approaches the electromagnets. Here, the attraction of the electromagnets is used for supporting the weight of the steel plate and for imparting thrust to the steel plate. At the same time, adsorption of the steel plate to the electromagnets is prevented by jetting air on the steel plate from compressed air passages provided between the electromagnets and the steel plate. Also, a study on the support of thin steel plate by 4 electromagnets (Denki Gakkai Sangyo Oyo Bumon, Zenkoku Taikai Yokoshu, July 1989, p915) and the development of a system which guides steel plate without contact using specially shaped electromagnets (Japan Laid-Open Patent Gazette: Laid-Open Patent No. Heisei 2-270739) are in progress.
However, with these techniques, the systems are complex, and the range of dimensions and weights of steel plate which can be transported is restricted. Also, it is presumed that the transporting of various weights and types of steel plate over long distances will be difficult.
As described above, when transporting steel plate without any scratching with devices which use mechanical contact, large amounts of labour and time are required for maintenance, shock prevention during transport, etc. Also, with prior art non-contact transport devices, there are problems such as that the dimensions and weights of transportable steel plates are limited, the systems are complex and long-distance transport is difficult.